The primary responsibilities of Core B are to provide the patient population that will be studied in the four research projects and to establish the technical and statistical support for all investigators. The four research projects are highly interdependent and interrelated. Each project depends on the questions and data generated by the other projects to answer the research questions addressed in their specific aims. They also use the same patient populations to address the overall goals of the Clinical Research Center as well as the specific aims of each project. This section will describe the extensive preoperative evaluation for subject accrual, specific populations to be studied, the cochlear implants to be used during the research protocol, and the general methods of the overall study design and time- line of subject involvement. The overall statistical design, data management and technical support are discussed. A description of the specific research questions and how each project is interactive and dependent on other projects are presented in the individual projects.